Sixth Doctor's sonic screwdriver
The Sixth Doctor once carried an unspecified replacement model for the sonic screwdriver, but had to leave it tied to the side of a video camera in a dungeon cell in order for it to keep the visual feed disabled. (PROSE: The Nightmare Fair) He later carried another sonic model during his adventures with Crystal, Jason, and Zog. (AUDIO: The Ultimate Adventure)
Uses
The Sixth Doctor's screwdriver could be used to disable a video camera indefinitely, (PROSE: The Nightmare Fair) close and seal Dalek doors, (AUDIO: The Ultimate Adventure) and repair the TARDIS control console. (AUDIO: The Ultimate Adventure) He once attempted to use it to free the American Envoy from the Dalek laser wall, but this failed. (AUDIO: The Ultimate Adventure)